GIP (Gastric inhibitory polypeptide or glucose-dependent insulinotropic peptide) is one of the gastrointestinal hormones which belong to a glucagon secretin family. GIP is referred to as incretin along with GLP-1 (glucagon-like peptide 1) and has been reported to be secreted from K cells located in the small intestine upon ingestion of lipid and carbohydrate. GIP is also known to possess inhibitory actions against gastric acid secretion and gastric motility (Non Patent Documents 1 to 3). Therefore, it is considered that inhibition of the increase of GIP is effective to promote postprandial digestion and to improve a heavy feeling in the stomach.
According to the previous studies, 3-bromo-5-methyl-2-phenylpyrazolo[1,5-a]pyrimidin-7-ol (BMPP) is known to be a substance inhibiting the functions of GIP, and guar gum or the like is known to be a substance inhibiting the postprandial secretion of GIP (Patent Document 1 and Non Patent Documents 4 to 9). In addition, in recent years, (Pro3) GIP has been known to be a GIP receptor antagonist. However, the safety and effectiveness of these substances have not been sufficiently confirmed.
Meanwhile, perilla and flaxseed are annual plants belonging to Labiatae and Linaceae, respectively. The fat or oil obtained from these plants is characterized in that α-linolenic acid accounts for 50% or more of the constituent fatty acid. Alpha-linolenic acid is one of the ω3-type highly unsaturated fatty acids, which has been reported to possess a function, for example, to enhance secretion of adiponectin (Patent Document 2). Furthermore, it has been reported that the nutrient composition containing protein, lipid such as perilla oil, and carbohydrate possesses an inhibitory effect against the increase of blood glucose level (Patent Document 3) and that perilla oil, linseed oil or the like possesses a tendency to decrease the visceral fat (Patent Document 4).
As for the relationship with GIP, it is known that a long chain fatty acid having 18 or less carbon atoms, such as oleic acid, linoleic acid, linolenic acid, or the like enhances secretion of GIP in blood (Non Patent Document 10).
However, the relationship between fat or oil abundant in α-linolenic acid and secretion of GIP has not been reported at all.